Production of motor fuels



Patented Jan. 11, 1944 Mathias. Pier, Heidelber Mannheim. Germany;

ustodian erty g, and Ernst Donath, vested in the Alien Prop- No Drawing. Application October 1, 1940,8erial No. 359,231. In German 7 ooiobcrl, 1939 1 Claim. ('01. 190-53)- The present invention relates to a process for the production of motor fuels.

It is known that hydrocarbon mixtures containing naphthenic hydrocarbons and boiling mainly within the boiling range of middle oils,

1. e., between about 200 and about 325 C., can

be converted into low-boiling hydrocarbon oils of the gasoline type by cracking them at a temperature above 400 C.'in the presence of stationary catalysts. In this process, however, the catalyst loses efllciency already after a short use, owing to the deposition of high molecular weight polymerization products to such an extent-that it must be reactivated or regenerated by the removal of these products. An excessive formation of undesirable deposits upon the catalyst can only be avoided by performing the reactivation oi the catalyst after a short use for the desired reaction. It was only by the development oi the catalytic destructive hydrogenation in the gas phase that it has become possible to convert middle oils into gasolines practically without the catalysts suffering a decrease of activity. Unlike the ordinary catalytic cracking process, however, the destructive hydrogenation must be carried out in apparatus capable oi withstanding high pressures; besides, since hydrogen is consumed 1 in the reaction, means tor its production must be provided.

We have now found that naphthenic hydrocar-.

bon mixtures substantially oi the middle oil boiling range can be cracked under'such reaction conditions that, though hydrogen is present, there is no net consumption thereof, that high pressure is not needed, thatthe catalyst remains active for remarkablylong periods of time and that gaseous hydrocarbons are formed to a comparatively slight extent only. For this purpose,

the initial materials, while in a vaporous state,

are passed over one or more of the oxides of the metals oi the 2nd to the 6th group of the periodic system, at temperatures between 440 and 550 (2., together with hydrogen, under a total pressure between about 25 and about 90 atmospheres and a partial pressure of hydrogen which "amounts to from about 30 to about 50 per cent of the total pressure and lies below 30, preferably below 20 atmospheres, and they gases containing hydrogen As initial materials may be mentioned hydrocarbon mixtures, approximately of the middle leaving the reaction space are returned thereto,

terial, over the catalyst, at intervals, for some time phalt-base mineral oils or from destructive hydrogenation products of mineral oils, tars or coals. The specific gravity of the fractions boiling i'rom about 290 to about 310 C. or from about 250 to'about 270 0., contained in the initial materials, advantageously amounts to more than 0.85 and 0.83, respectively.

As catalysts may be used, for example, the oxides of chromium, molybdenum orvanadium or mixtures thereof, as for example mixtures of oxides oi chromium and vanadium, which are deposited on carriers, as for example active silica, bleaching earth, kieselguhr, magnesia or zinc oxide and preferably on active alumina. Natural or artificial aluminum and/or magnesium silicates, which may be provided with a metal oxide, especially one of those cited above, may also be employed.

The total pressure, preferably ranges between about 80 and about atmospheres, especially bethe operation, an addition 01' hydrogen. is not required, since no hydrogen is consumed and the quantity returned will suflice to prolong the activity oi the catalyst. Ii any excessive amounts oi undesired gases, especially gaseous hydrocarbons, as for example methane, should accumulate in the hydrogen to be returned, they may be removed wholly or in part, for example by washing. For this purpose, a partial current of the gases leaving the reaction chamber may be branched of! and purified and theresulting hydrogen returned to the reaction chamber either alone or together with unpuritled gas.

The reactivation of, the catalyst cannot, indeed, be entirely dispensed with, but the periods of operation are considerably longer than when working without hydrogen. They are at least two hours, in general from 4 to 20 hours, and may even be considerably longer, say several days. It

,may beoi' advantage to pass the gas containing hydrogen returned alone, i. e., without initial ms.-

at the reaction temperature, whereby the catalyst is partly reactivated and the necessity 01 a complete reactivation is put 01!. I

The reactivation is accomplished in known manner by means or gases containing oxygen, the percentage of oxygen in the gas being preterably low initially and increased gradually, at an elevated temperature and, if desired, under pressure. The catalysts mentioned abov may be reactivated many times.

The products obtained by a single pass through the reaction chamber consist to the extent of about 25 to 40 per cent of gasoline and or an aromatic middle oil. According to the choiceoi the conditions the yield of gasoline may be increased or diminished. The resulting gasolin is a non-knocking motor fuel. The aromatic middle oil may be returned to the reaction chamber or converted into non-knocking motor fuels by any.

oxide under a total pressure of 50 atmospheres and a hydrogen partial pressure of about 18 atmospheres at a temperature of 505 C. The gaseous reaction products obtained which contain 43 per cent or hydrogen are returned to the reaction chamber in an amount of 0.6 cubic meter per kilogram oi, initial material. The chamber is filled with pieces of catalyst which are slowly passed therethrough. The catalyst remains in the reaction chamber for about 8 hours.

Besides 13.5 per cent of gases, a liquid product is obtained which consists of 27 per cent of gasoline and '13 per cent of middle oil. The middle oil is low in hydrogen and of aromatic nature: the gasoline contains 32 per cent of constituents boiling up to 100 0., possesses an octane number 01' 82 atnd a content of oleiines amounting to 1.5 per cen What we claim is:

In a process for the production or knock-resistant motor fuels from hydrocarbon oils by catalytic vapor phase cracking at elevated temperatures and pressures in the presence 0! hydrogen and recycling of hydrogen-containing reacted gases. the improvement which comprises using in combination a naphthenic starting material boiling mainly within-the boiling range of middle oils, an oxide of a metal selected from the 2nd to the 6th group of the periodic system as the catalyst, a temperature of 440-550 C., a total pressure of 25-90 atmospheres, a hydrogen partial pressure of less than 30 atmospheres and amounting to 30- or the total pressure and a gas recycle ratio of 0.3-1.5 cubic metersper kilogram or starting material, partly reactivating the catalyst by passing the hydrogen-containing recycle gas over the catalyst at the smoking temperature without the addition of initial material and completely reactivating the catalyst after a reaction time of at least two hours.

MA'I'HIAS PIER.

ERNST DONATE. 

